Frequency Meter Circuits
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This is a CMOS-compatible (and hopefully also TTL) input featuring over- and under-volatage protection. Schmitt triggers are used to allow for input with long transition times. Verified to work up to 30MHz... -
The counter makes use of 5 cascaded CD40110 which combine a decade counter, a display latch and a 7 segment LED driver in a single chip. (The decimal points are driven by IC8x. ) The counter allows up and down counting (although only up counting is used in.... -
The divider design is pretty self-explanatory. One can choose between division by 1, 10 or 100 or no output (tied low) using the CONTROL input connected to the analog multiplexer HC4052. AC04are used to drive 3 indication LEDs as well as to buffer the.... -
This is basically 4 nearly identical debounced switches. The 2 resistors and one capacity at the input of each Schmitt trigger are used for debouncing the switches. The output is then fed into a D-type flip-flop which uses feedback to change the state (LOW.... -
The master mode selection switch is IC6 which switches the 4 mode LEDs (which also correspond to the measured unity, i. e. kHz, counts, milli-seconds or seconds) as well as the input for the divider and the counter : For standard frequency counter mode.... -
The lower schematic is a pretty standard bidirectional rectifier together with capacitors and a 7805 as a fixed 5V source which supplies all the electronic in the frequency counter. For "security reasons" a fuse is used. The upper diagram shows the main.... -
The oscillator provides a 1MHz and a 1khz clock. The 1MHz clock is used as the clock for the microcontroller and as timebase for millisecond measurement. I use a 2MHz and divide it by 2 in order to guarantee a 50% duty cycle. Then three halve HC390 are used.... -
The Model LM-13 Crystal Calibrated Frequency Indicating Equipment has been specially designed to provide a simple, accurate and reliable frequency indicating equipment of the crystal calibrated type for use in the (U. S. ) Naval radio service. It is.... -
This is a successor of the PIC16C71 4-digit LED f-counter & V-meter. Some hard to find parts used in the previous version, which are out of production for some time, has been omitted. A rather early PIC16C71 has also been replaced by 28-pin device PIC16F876..... -
As equipment becomes increasingly more compact, designers are often obliged to follow suit by reducing the size of displays. At some point, the usefulness of the display can become compromised. I, for one, dislike having to peer intently at tiny displays in.... -
I needed an excuse to use the soldering iron so I figured that I might as well as make a frequency counter which is something that I`ve always wanted, but lacked in my lab. Here`s the schematic. I drew it up in OrCAD PSpice a while back. Since then, I have....
New Circuits
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This project fits more for custom made battery casing that can have more space to hide things inside. This switch with few alterations can be used for any other project as well but is designed based on e-bike needs! This project use a clever functionality of.... -
The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is.... -
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to.... -
Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This.... -
The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the.... -
The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound,.... -
In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the.... -
This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power.... -
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower.....
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